Fundamentals of DBMS

Database
Management
System
Dr. Kamal Gulati
(DBM
S)

Contents
• What is Data ?
• What is Information?
• Data Models, Schema and
Instances
• Components of Database
System
• What is DBMS ?
• Database Languages
• Applications of DBMS

Introduction
• DBMS stands for Database
Management System.
• DBMS is a software system
for creating, organizing and
managing the database.
• It provides an
environment to the user
to perform operations on
the database for creation,
insertion, deletion,
updating and retrieval of
data.

What is
Data ?
A collection of raw facts
and figures.
Raw material
that can be
processed by
any computing
machine.
A collection of
facts from
which
conclusions
may be drawn.
Data can be
represented in
the form of:
numbers,
Alphabets &
Symbols which
can be stored
in computer's
language.
•i.e. Kamal
Gulati,
kamal@123

What is
Information?
Knowledge acquired through
study or experience.
Information helps human beings
in their decision making.
Systematic and meaningful
form of data.

Database
• A repository of logically related and similardata.
• An organized collection of related information so that it
can easily be accessed, managed and updated.
• E.g.:
• Dictionary
• Airline Database
• Student Database
• Library
• Railways Timetable YouTube
(All videos of NIOS)

Data Models, Schema and
Instances
 Data Models:
• Describes structure of the database.
• Aim is to support the development of
information systems by providing the
definition and format of data.
• If the same data structures are used to
store and access data then different
applications can share data.
• Classification:
1. High-Level Model
2. Representation Model
3. Low-Level Model

1. High-Level Model
• Ensures data requirement of the users.
• Not concerned with representation,
but its conceptual form.
• Three Imp terms:
• Entity: Any object, exists physically or conceptually.
• Attribute: Property or characteristic of entity.
• Relationship: Association or link b/w two entities.
• These 3 terms make Entity-Relationship Model.

Entity-Relationship (E-R) Model
College Principal
College
Student C
Student A
Student B
College 3
College 2
College 1
Course C
Course B
Course A
Student CourseAdmissio
n
Stud_Nam
e
Stud_Roll
No
Course_I
d
Course_Na
me
Relationships
E-R diagram

2. Representation Model
• Representation of data stored inside a
database.
• Describes the physical structure of the
database.
• It uses the concepts which are close to
the end-users.
• Classification:
A. Hierarchical
B. Relational
C. Network

A. Hierarchical Database Model
• Developed by IBM, is the Oldest database model.
• Represented using a tree-diagram.
(Parent-child relationship)
• Each box is called a Node
• The nodes represent a record type.
• A line connecting nodes
represents the link.
Director
Manager
(Market.)
Manage
r
(Sales)
Manager
(HR)
Area
Manager
1
Area
Manage
r 2
Area
Manage
r 3
Sales Exe.
1
Sales Exe.
2
Sales
Representative

Cont…
• Parent-child type is suited for One-to-many
relationship between two entities.
• But difficult to implement
many-to-many relationship.
e.g.:
IMS system from IBM.
*IMS -Information Management System
Director
Manager
(Market.)
Manage
r
(Sales)
Manager
(HR)
Area
Manage
r 1
Area
Manage
r 2
Area
Manage
r 3
Sales Exe.
1
Sales Exe.
2
Sales
Representative

B. Relational Database Model
• Simplest and the most common model.
• Developed in 1970 by E.F. Codd, it became commercial in
the 80s.
• Data elements are stored in
different tables made up of
rows and columns.
Roll No Name Surname Section
1001 Kamal Gulati D
1002 Rahul Singh A

Cont…
• Terminologies:
-Data Values: alphanumeric raw data (Kamal)
-Columns: fields (item or object that holds the data)
-Rows: record (a group of data for related field)
-Table: collection (all records & fields)
-Key: identifier (uniquely identifies a row in the
table. It can be value of a single or multiple column.
e.g.:
DB2, ORACLE, SQL Server.
Roll No Name Surnam
e
Section
1001 Kamal Gulati D
1002 Rahul Singh A

C. Network Database Model
• Represented using a Data-Structure Diagram.
• Boxes represents the records & lines the links.
• Based on owner-member relationship
• Members of an owner may
be many but for many membe
owner is one.
• Can represent one-to-one and
many-to-many as well.
Teacher 1 Teacher 2 Teacher 3
Course A Course B Course C
Student 1 Student 2 Student 3

Cont…
• One-to-many relationship is converted into a set of
one-to-one.
• Also, many-to-many is
converted into 2 or more
one-to-many
relationship.
e.g.:
IDMS, IMAGE.
*IDMS: Integrated Database Management System
Teacher 1 Teacher 2 Teacher 3
Course A Course B Course C
Student 1 Student 2 Student 3

Cont…
Schema:
- Logical structure of the database.
- Doesn't show the data in database.
- Classification:
1. Physical
2. Conceptual
3. External

Cont…
1. Physical Schema:
-Describes the physical storage of database.
-Not in terms of blocks or devices, but describes organization of files,access path etc.
2. Conceptual Schema:
-Describes structure of whole database.
-Describes entities their relationships and
constraints.
3. External Schema:
-Provides a user's view of data.
-Shows relevant info particular to user, hides
rest of the info.
-one or more levels.

 Instances
Actual data contained in database at a particular point of
time.
The database state is also called extension of the schema.

Components of Database System
Component
s of
database
User
s
Softwar
e
Hardwar
e
Dat
a
• Users- People who interact with the
database:
- Application Programmers.
- End Users.
- DataAdministrators.
•Software- Lies between the stored data
and the users:
- DBMS.
- Application Software.
- User Interface.

Cont…
• Hardware- Physical device on which
database resides.
e.g.:
Computers, Disk Drives,
Printers, Cables etc.
• Data- numbers, characters, pictures.
e.g.:
NIOS, 1008, Noida, India.
Component
s of
database
User
s
Softwar
e
Hardwar
e
Dat
a

What is DBMS ?
• A set of programs to access the interrelated data
• DBMS contains information about a particular
enterprise.
• Computerized record keeping system.
• Provides convenient environment to user to
perform operations:
-Creation, Insertion, Deletion,
Updating & Retrieval of information.

Database Administrator (DBA)
• Individual or a group, having centralized control of the
database.
• Has a good understanding of database and
coordinates all activities of the database.
• Functions:
-Defines schema.
-Defines storage structure and access method.
-Modification of both.
-Granting user authority to access the database.
-Monitoring performance and responding to changes.

Database Languages
• Once data is filled, manipulation is required
(insertion, deletion, modification of data)
• For these, a set of languages is provided by DBMS:
1. Data Definition Language.
2. Data Manipulation Language.
3. Data Control Language.

Cont…
1.Data Definition or Description
Language (DDL):
-Used by DB designers to define schema.
-DDL compiler converts DDL statements
and generate a set of tables which are
stored in.
e.g.: CREATE, ALTER & DROP
2. Data Manipulation Language (DML):
-For accessing and manipulating the
data.
e.g.: CONNECT, SELECT, INSERT,
UPDATE, DELETE, EXECUTE

3. Data Control Language (DCL):
-Similar to a computer programming language
used to control access to data stored in a
database.
-e.g.: GRANT, REVOKE

Database System Architectures
• The journey from big mainframe to pc has
also evolved the database and its architecture.
• Classification:
1.Centralized DBMSArchitecture
2.Client-ServerArchitecture
3.Distributed Databases

1. Centralized DBMS Architecture
• Traditional form, all data, functionality,
apps are located on one machine.
• Access via communication links.
Enterpris
e
databas
e

2. Client-Server Architecture
• Involves a client and a server.
• Clients are PCs or workstations.
• Servers are powerful computers, can manage files,
printers, e-mails.
• Client interacts server when additional functionality
Doesn'texits in its ownmachine.
Client
User interface
Application program
Database server
Database tables
Application server

3. Distributed Database Architecture
• Decentralized functionality, distributed among many
computers.
• Storage computers are at diff. geographical locations.
Enterpris
e main
database
Fragme
nt
Fragme
nt
Fragme
Fragme
nt
Fragme
nt

Advantages of DBMS
1. Controlling Data Redundancy: Data is recorded in
only one place in the database and it is not
duplicated.
2. Data Consistency: Data item appears only once,
and the updated value is immediately available to
all users.
3. Control Over Concurrency : In a computer file-
based system in updating, one may overwrite the
values recorded by the other.

Advantages of DBMS Contd.,
4. Backup and Recovery Procedures: automatically
create the backup of data and restore data if required.
5. Data Independence: Separation of data structure of
database from application program that uses the data is
called data independence.

Disadvantages of DBMS
1. Cost of Hardware and Software: Processor with
high speed of data processing and memory of large
size is required.
2. Cost of Data Conversion: Very difficult and costly
method to convert data of data file into database.
3. Cost of Staff Training: A lot of amount for the
training of staff to run the DBMS.

3. Appointing Technical Staff: Trained technical persons
such as database administrator, application
programmers, data entry operators etc. are required to
handle the DBMS.
4. Database Damage: All data is integrated into a single
database. If database is damaged due to electric failure or
database is corrupted on the storage media, then your
valuable data may be lost forever.
Disadvantages of DBMS Contd.,

Examples of DBMS
• Some of the commonly used DBMSs are:
-Oracle, IBM’s DB2, Microsoft's SQL Server and
Informix.
• Some of the desktop-based DBMSs are:
-Microsoft FoxPro, Borland dBase and
MicrosoftAccess.

Applications of DBMS
1. Airlines and Railways: Online databases for
reservation, and displaying the schedule
information.
2. Banking: Customer inquiry, accounts, loans, and other
transactions.
3. Education: Course registration, result, and other
information.
4. Telecommunications: Communication network,
telephone numbers, record of calls, for generating
monthly bills, etc.

Applications of DBMS Contd.,
5. E-commerce: Business activity such as online shopping,
booking of holiday package, consulting a doctor, etc.
6. Human resources: Organizations use databases for
storing information about their employees, salaries,
benefits, taxes, and for generating salary checks.

1. Introduction to Databases
2. Fundamentals of Data Modeling and Database
Design
3. Database Normalization
4. Types of keys in database management system
5. Distributed Database
More Contents on Database

For any Query related to the subject
drkamalgulati@gmail.com

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